I know we've all looked into the guild banks or at the limited number of guild ranks and pondered how to make them better. Please feel free to post suggestions to the dev's on what could be added to make things better.
List of Suggestions to Improve Guild Bank
Add the ability to expand each Repository to basically double its current size
Add the ability to donate Astral Diamonds from guild members to the first tab
(More of a Bug) Enhance the permissions system (had a member try to withdraw an item right after I changed the permission and it said he had exceeded his total withdrawal for the day when he hadn't pulled anything).
List of Suggestions to Improve Guild Manageability
Add the ability to add ranks to the guild, ultimately allowing for special ranks to be added by guild leaders to fulfill special titles or jobs within the guild to be displayed within the game. This would allow for Crafters to be given withdraw privileges in a crafting mats repository but not any other tab because of their rank. This is just one of the many applications this freedom would allow for. A good limit would probably be around 30 or so (for instance Sinister Swarm, with out going into special positions, has 9 ranks within our community, and with special positions, has 27 potential positions).